Deoxygenation of hydrocarbons



Sept. 26, 1950 w. N. AXE

DEoxYGENATIoN oF HYDRocAaBoNs Filed June 10, 1946 ATTORNEYS Patented Sept. 26, 1950 UNITED STATES AT ENT OFFICE DEOXYGENATION OF HYDROCARBONSv William N. Axe, Dewey, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware `Claims.

l. This invention relates to improvements in processes for removing oxygen from hydrocarbon materials. In one particular aspect it relates to novel reagents for absorbing oxygen from hydrocarbon materials and. in another` particular aspect it relates tocontinuous processes for removing oxygen 'from hydrocarbon streams.

Oxygen is often present in hydrocarbon streams as molecular` oxygen in simple solution, as peroxides and inY other less clearly understood forms which are in equilibrium with dissolved oxygen. The term` looselycombined oxygen??` as yused in this disclosure and claims is hereby defined as that oxygen which may :be derived from peroxides and other compounds as a result of equilibrium .reactions with dissolved molecular oXygen. This invention is directed to the removal of dissolvedoxygen .andsuch loosely combined oxygen. from hydrocarbon'materials.

In many commercial processes and products the presence of dissolved. or loosely. combined oxygen in hydrocarbon .materials 4is very objectionable. For example it has long beenrecognized that the presence ordissolved oxygen .is a major contributingfactor in gasoline `pipe line corrosion. Itis also -well established that the formation oi peroxides lis theinitial stage .in the formation Aof gum in-cracked gasoline. The copending applicationsof Legatski and Crawford, Serial No.6l6,930,-iled Sept.- 171945, novvPatent Number'2,468,986, `issued May v3, 1949, and Crawford and .Morris,- Serial No. 617,870, filed Sept. 2l, 1945, novv Paten-t Number 2,463,601, issued March 8, 1949,shovv that-dissolved oxygen is a'factor-causing unpleasant -odor to develop in mixtures voi highly branched -paraiiin hydrocarbons.

Heretofore catalyticreductionl processes and liquid absorptionA systems utilizing -falkaline cuprous salts have been availableefor -removingoxygen from hydrocarbon streams. These processes have the'great disadvantages ofbeing relatively expensive Vand-are often diicult to Operateeiciently: A-Lcheap, convenient and -eicient process for Vremoving dissolved,- admixed and vloosely combined foxygen is-a greatly needed improvement in-the art and may eiTect Iconsiderable conservation of natural gas resources. The removal-of oxygen from gaseous hydrocarbons, on an industrial scale,has not-hitherto been practicedvbeeause of the lack of an economical process. Expensive catalytic reduction V`processes operatingaat relatvelyhigh temperatures ordinarilycannot-bejustied economically for the treatment of natural gas-streams- As a resultloi this situation many gas wells are abandoned because the oxygen content of the gas precludes normal utilization in the natural gasoline and lfuel -gas industries.

It. is-an object of this invention to provide a,

continuous process for removing dissolved, admixed and loosely combined oxygen from liquid or gaseous hydrocarbon streams.

Another object is to provide la novel reagent for removing dissolved, admixed and loosely combined roxygen from hydrocarbon materials.

Another object is to provide a process for removing dissolved, admixed and loosely combined oxygen from hydrocarbon materials by use'lof a solid reagent,

Still another object is-to provide a process for removing dissolved, admixed and'loosely combined oxygen from hydrocarbon materials Which is cheap, convenient and efcient in operation.

Other objects and advantages will become apparent to those skilled. in the artas this disclosure proceeds.

I have found that certain organo-cobalt chelate compounds, which are known to absorb oxygen from air at relatively low temperatures at atmospheric and higher pressures and to give up such absorbed oxygen' at relatively high temperatures at atmospheric and lower pressures, .are also effective for removing dissolved, admixed and loosely combined .oxygen from hydrocarbon materials, in spite of the very low partial pressure exerted by oxygen in such materials.

A typical organo-cobalt chelatecompound. suitable for such removal .of oxygen. .is disalicylalf ethylenediimine-cobalt, which has the structure The above compound is commonly known by its proprietary name Salcomine Derivatives of disalicylalethylenediimine-cobalt having substituents in the 3 and/ or -positions of thewbenzene nuclei are also effective. Such substituents may include: hydroxy, alkoxy, alkyl, nitro, halogen and combinations. of these groups; and `whena plurality of substituentsare present they may be like or unlike. While disalicylalethylenediimine-.cobalt is. the most practical reagent from the present standpoint of cost and availability, 3,- fiuoro disalicylalethylenediimine-cobait, 3-ethoxy disalicylalethylenediimine-cobalt and 3-methoxy-disalicylalethylenediimine-cobalt are somewhatmore eiiicient as oxygen-removing agents.

The chemistry of the preparation of the organo-cobalt chelate compounds of this invention is, in general, old in the art. Essentially the steps involved are: (l) interacting salicylaldehyde or an analogthereof with an aliphatic diairlinel such as ethylenediamine in an aqueous medium which is about 4.5 normal with respect to sodium hydroxide and which contains about 0.28 pound of sodium acetate trihydrate per pound of sodium hydroxide; (2) adding this solution to a dilute solution of cobaltous chloride (about 1.5 weight per cent) in dilute acetic acid (about 2 weight ,per cent) maintained at about 80 C.; and (3) cooling the reaction mixture and collecting, washing and drying the precipitated product.

It is possible to use the dried precipitate in finely divided form for removing oxygen from hydrocarbon materials but I prefer to convert it to a more efficient contact reagent by mixing it with a ller and binder and pelleting the resulting mixture.

In many instances, however, it is preferred to support the organo-chelate compound on a carrier, whereby greater resistance to attrition, lower pressure drop through the reagent bed and more eicient contacting with a hydrocarbon stream owing through a bed of reagent may be realized. Such a reagent may be prepared by impregnating an inert, porous, granular material such as fullers earth, bauxite, pumice or the like with a Schiffs base corresponding to the organo-cobalt chelate compound desired. The impregnated carrier is then soaked or sprayed with the dilute cobaltous chloride solution whereby the organocobalt chelate compound is formed in situ within the pores and on the surface of the carrier material. The reagent is then washed and dried prior to use.

Another method for preparing contact reagents is to tumble asbestos fiber with dry powdered organo-cobalt chelate compound.

Drawing The attached drawing illustrates diagrammaticallv one preferred manner of conducting the process of my invention. Referring thereto, a hydrocarbon stream enters via line I. This feed stream may contain any of the usual commercial hydrocarbon materials, either liquid or gaseous, containing dissolved, admixed and/or loosely combined oxygen and may contain hydrogen sulfide, mercaptans, and other impurities. Since hydrogen sulde and mercaptans tend to inactivate the organo-cobalt reagent and water tends to interfere with proper oxygen absorption, these substances when present must be removed by pretreatment steps.

The incoming feed is accordingly passed via line 2 to a hydrogen sulfide removal Zone 3. Tihe hydrogen sulfide free stream issues from zone 3 via line 4 and is conducted to a sweetening zone 'I via lines I and 6 and there the mercaptans present are converted to disuldes. The stream passes from zone 'I via lines 8, I and 9 to drying zone II where it passes over a suitable drying agent such as calcined bauxite. The processes of removing hydrogen sulfide, sweetening and drying may be conducted in zones 3, 'I and I I by any conventional methods known to be eiective. Treatment of the feed in either or all of zones 3, I and I I may be omitted when the corresponding impurity is absent from the incoming feed.

The 'hydrocarbon stream, free from hydrogen sulfide, mercaptans and water is conducted via lines I2 and/or I and I3 to an oxygen removal zone. This zone may have any arrangement desired which secures intimate contact of hydrocarbon stream and reagent but is preferably a tower packed with the organo-cobalt chelate contact reagent prepared as described above.

After contacting the organo-chelate reagent the hydrocarbon stream is withdrawn via line l5 to storage, pipe line or use as desired.

Flow through Zone I4 may be continued until the organo-chelate compound has absorbed about 4 per cent of its weight in oxygen. Flow of the incoming stream is then shunted to a second Zone I6 similar to zone I4 and operated in the same manner while regeneration of the organo-cobalt reagent is conducted in zone I4.

This is accomplished by passing air or inert gas via line 20 through a furnace 2I and leading the resulting heated air via lines 22 and 23 to Zone I4. Regeneration of the reagent is accomplished by heating the reagent to a temperature in the range from 175 to 300 F., but the range from about 200 to about 250 F. is preferred because of convenience, speed of regeneration and ease of preventing damage to the reagent by excess localized heat. Used air and oxygen are vented through line 26. At temperatures much above 300 F. decomposition of the reagent occurs rapidly, but up to 300 F. decomposition is negligible. Regeneration may be conducted at pressures below atmospheric if desired, and longer reagent life may sometimes be secured by such low pressure operation.

When regeneration is complete residual oxygen is swept out of zone I4 by methane or other suitable gas introduced via lines 30 and 23. The hydrocarbon stream is again shunted to zone I4 and Zone I6 is placed on regeneration as described.

The temperature in the oxygen removal zone is maintained between 32 F. and 115 F. but should not be as high as the boiling point of a liquid material being treated. For instance oxygen removal from gasoline stream should be conducted at temperatures below about F. The rate of flow through the bed of reagent will be variable and must be adjusted according to the temperature employed, the quantity and type of oxygen present and the completeness of oxygen removal desired. For example, pipeline gasoline often contains about 10 cc. at standard temperature and pressure, of dissolved gaseous oxygen per liter of gasoline and this may be removed bv treatment in the temperature range from 32 to 90 F. In the lower part of this range a flow rate of about l0 volumes of liquid per volume of reagent per hour are eiective. However, it is more convenient and practical to operate the oxygen removal zone at about '70 to 80 F., and at this temperature somewhat lower rates of flow should be used. The general rule is that higher temperatures cause slower absorption of oxygen by the reagent.

Still slower rates Iof flow should be used when relatively large ouantities of peroxides are present in order to permit decomposition of these materials and removal of the resulting oxygen. Very slow rates of flow are necessary when all traces of oxygen are to be removed as is sometime desirable in certain alkylate materials. In such cases when operating at about 70 to 80 F., flow rates of about 1 to 2 liquid volumes per volume of reagent per hour is recommended. In all cases the rate of ow may be regulated by examining the eluent hydrocarbon stream by methods well known in the art to determine the oxygen content thereof and adopting the highest rate of flow which will give the degree of oxygen removal desired.

Having described my invention and explained its operation, I claim:

1. A process for removing free and loosely combined oxygen from a liquid hydrocarbon stream free from hydrogen sulde, mercaptans 'and water and containing not more than l0 c. c. of said oxygen per liter of said hydrocarbon stream which comprises: passing said hydrocarbon stream into an oxygen removal zone; therein intimately contacting said stream at a temperature of from 32 F. to 115 F. and under pressure of from atmospheric to 100 pounds per square inch gauge with a solid reagent comprising a disalicylalethylenediimine-cobalt supported on a porous, inert, granular material, and prepared by impregnating said granular material with a Schiffs base corresponding to said compound desired, contacting said impregnated carrier with a dilute cobaltous chloride solution whereby the disalicylalethylenediimine-cobalt compound is formed in situ within the pores and on the surface of the carrier material.

2. A process of removing free and loosely com- .bined oxygen from a liquid hydrocarbon stream containing hydrogen sulfide, mercaptans and water and not more than cc. of said oxygen per liter of said hydrocarbon stream which comprises: pretreating such hydrocarbon stream to remove hydrogen sulfide, mercaptans and water; passing the resulting pretreated stream to an oxygen removal zone; there intimately contacting said stream at a temperature in the range from 32 F. to 115 F. and under pressure in the range from atmospheric to 100 pounds per square inch gauge with a solid reagent comprising a disalicylalethylenediimine-cobalt supported on a porous, inert, granular material, and prepared by impregnating said granular material with a Schiffs base corresponding to said disalicylalethylenediimine-cobalt compound desired, contacting said impregnated carrier with a dilute cobaltous chloride solution whereby the said disalicylalethylenediimine-cobalt compound is formed in situ within the pores and on the surface of the carrier material; separating said reagent together with absorbed oxygen from said hydrocarbon stream, separating oxygen from said reagent by heating the reagent to a temperature in the range from 175 F. to 300 F. under a pressure of not more than one atmosphere; and contacting the resulting deoxygenated reagent with said hydrocarbon stream in an oxygen removal zone.

3. The process of removing free and loosely combined oxygen from a liquid hydrocarbon stream containing hydrogen sulfide, mercaptans and water as impurities and not more than 10 c. c. of said oxygen per liter of said hydrocarbon stream which comprises: pretreating such .hydrocarbon stream to remove hydrogen sulfide, mercaptans and water; passing the resulting pretreated stream to an oxygen removal Zone; and intimately contacting said stream at a temperature in the range from 32 F. to 115 F. and under pressure in the range from atmospheric to 100 pounds per square inch gauge with disalicylalethylenediimine-cobalt supported on porous, inert, granular bauxite, and prepared by impregnating said .granular material with a Schiffs base corresponding to said disalicylalethylenediimine cobalt, contacting said impregnated carrier with a dilute cobaltous chloride solution whereby the said disalicylalethylenediimine-cobalt is formed in situ within the pores and on the surface of the carrier material; separating said reagent together with absorbed oxygen from said hydrocarbon stream, separating oxygen from said reagent by heating the reagent to a temperature in the range from 175 F. to 300 F. under a pressure of not more than one atmosphere; and contacting the resulting deoxygenated reagent with said hydrocarbon stream in an oxygen removal zone.

4. The process for removing free and loosely combined oxygen from a hydrocarbon stream containing hydrogen sulde, mercaptans and water as impurities which comprises: pre-treating such hydrocarbon stream to remove hydrogen sulde, mercaptans and water; passing a resulting pre-treated stream to an oxygen removal zone; therein intimately contacting said pretreated stream with a solid reagent comprising a disalicylalethylenediimine-cobalt at a temperature from 32 F. to 115 F. and under a pressure in the range of from atmospheric to pounds per square inch gauge; separating said reagent together with absorbed oxygen from said hydrocarbon stream; separating oxygen from said reagent by heating said reagent to a temperature in the range from F. to 300 F. under a pressure of not more than 1 atmosphere; and reintroducing a resulting deoxygenatedy reagent into said hydrocarbon stream passed into said oxygen removal zone.

5. The process of removing free and loosely Y combined oxygen from a liquid hydrocarbon stream containing hydrogen sulde, mercaptans and water and not more than 10 c. c. of said oxygen per liter of said hydrocarbon stream which comprises: pre-treating such hydrocarbon stream to remove hydrogen sulde, mercaptans and water; passing a resulting pre-treated stream into an oxygen removal zone, and therein intimately contacting said stream at a temperature in the range from 32 F. to 115 F. and under a pressure in the range from atmospheric to 100 pounds per square inch gauge with 3-uoro-disalicylalethylenediirnine-cobalt supported on porous, inert, granular bauxite, and prepared by impregnating said granular bauxite with a Schiis base corresponding to said 3-iluoro-disalicylalethylenediimine-cobalt, contacting said impregnated carrier with a dilute cobaltous chloride solution whereby said 3-uoro-disalicylalethylenediimine-cobalt is formed in situ within the pores and on the surface of said bauxite; separating said reagent together with absorbed oxygen from said hydrocarbon stream, separating oxygen from said reagent by heating said reagent to a temperature in the range from 175 F. to 300 F. under a pressure of not more than 1 atmosphere; and contacting the resulting deoxygenated reagent with said hydrocarbon stream introduced Y into said oxygen removal zone.

WILLIAM N. AXE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS pages 252-260.

Bulletin (1938), vol. 13, Chem. Soc. of Japan, pages 579-591.

Bulletin (1938), vol. 13, Chem. Soc. of Japan, pages 252-259. 

1. A PROCESS FOR REMOVING FREE AND LOOSELY COMBINED OXYGEN FROM A LIQUID HYDROCARBON STREAM FREE FROM HYDROGEN SULFIDE, MERCAPTANS AND WATER AND CONTAINING NOT MORE THAN 10 C.C. OF SAID OXYEN PER LITER OF SAID HYDROCARBON STREAM WHICH COMPRISES: PASSING SAID HYDROCARBON STREAM INTO AN OXYGEN REMOVAL ZONE; THEREIN INTIMATELY CONTACTING SAID STREAM AT A TEMPERATURE OF FROM 32* F. TO 115* F. AND UNDER PRESSURE OF FROM ATMOSPHERIC TO 100 POUNDS PER SQUARE INCH GAUGE WITH A SOLID REAGENT COMPRISING A DISALICYLALETHYLENEDIIMINE-COBALT SUPPORTED ON A POROUS, INERT, GRANULAR MATERIAL, AND PREPARED BY IMPREGNATING SAID GRANULAR MATERIAL WITH A SCHIFF''S BASE CORRESPONDING TO SAID COMPOUND DESIRED, CONTACTING SAID IMPREGNATED CARRIER WITH A DILUTE COBALTOUS CHLORIDE SOLUTION WHEREBY THE DISALICYLALETHYLENEDIIMINE-COBALT COMPOUND IS FORMED IN SITU WITHIN THE PORES AND ON THE SURFACE OF THE CARRIER MATERIAL. 